Merge pull request matplotlib#2847 from tacaswell/subplot_doc

DOC : add link to `plt.subplots` from `Figure.add_subplot`

Author: efiring

lib/matplotlib/figure.py

@@ -892,6 +892,9 @@ def add_subplot(self, *args, **kwargs):
         *kwargs*) then it will simply make that subplot current and
         return it.
 
+        .. seealso:: :meth:`~matplotlib.pyplot.subplot` for an
+           explanation of the args.
+
         The following kwargs are supported:
 
         %(Axes)s